<div class="am-form-group am-form-file">
  <button type="button" class="am-btn am-btn-default am-btn-sm">
    <i class="am-icon-cloud-upload"></i> 选择要上传的文件</button>
  <input type="file" multiple>
</div>
 
<hr/>
 
<div class="am-form-group am-form-file">
  <i class="am-icon-cloud-upload"></i> 选择要上传的文件
  <input type="file" multiple>
</div>

$('input[type="file"]').change(function (event) {
    var that = this;
    var file = $(that)[0].files[0];
    if(file){
        $(that).prev().text(that.files[0].name);
        $(that).attr({ 'src': window.URL.createObjectURL(that.files[0]) });
    }
});

$('input[type="file"]').closest('div').hover(function(){
    if($(this).find('input[type="file"]').attr('src')){
        $('body').append('<div class="imgView" style="width: '+$(this).find('button').css('width')+';top: '+($(this).find('button').offset().top-210)+'px;left: '+$(this).find('button').offset().left+'px;height: 200px;position: absolute;text-align: center;line-height: 200px;z-index: 99999;background-color: rgba(51, 51, 51,0.6);"><img style="max-width: 90%;max-height: 90%;" src="'+$(this).find('input[type="file"]').attr('src')+'"></div>')         
    }
},function(){
    $('.imgView').remove();
});